William Keswick was an important figure in Jardine-Matheson's role in China and Japan, and in the London-based Matheson and Company, from the mid-nineteenth century onwards until his death in 1912, yet he has scarcely received the attention that might have been expected from this long involvement in East Asian trade. He is curiously absent from the current Dictionary of National Biography, though several of his Jardines’ relations are so honoured. His Who was Who entry, based on his own account of himself, is amazingly brief, omitting both his wives, and what many would see as his major role in the China Association, for example, though noting his onetime membership of the Hong Kong Legislative Council. His role as a Conservative MP from 1899 and his appointment as JP and High Sheriff for Surrey receive as much prominence as his work in Asia. His years in Japan, where he established Jardine's presence immediately after the 1858 treaties allowed foreign residence, go wholly unnoticed.

William Keswick was born on 1 January 1835, according to his Who was Who entry, though most sources say 1834, in the Scottish lowlands. A nephew of William Jardine, he attended Merchiston's school in Edinburgh, and went out to China in 1855, the first of five generations of the Keswick family to be associated with Jardines. His younger brother, James Johnstone Keswick, also joined the company in China. By that stage, Jardine, Matheson, which can trace its origins back to 1782 and a bewildering collection of intermediate names, was well-established on the Chinese coast, though faced with major rivals such as Dent and Company, and was distancing itself from its early role in the more questionable aspects of the China trade.

Naturally enough, Jardines was interested in the new trading possibilities opening up in East Asia in the 1850s, as the pressure increased on Japan to abandon its isolation. Before the treaties permitted formal trade with Japan, Jardines had traded in Japanese products usually through the Ryukyu islands or Taiwan, although there was also contact with Chinese merchants established at Nagasaki. The trade, officially forbidden by the Japanese authorities, was always small, but no doubt it served to whet appetites.

The earliest treaties with Japan, concluded by United States’ and British naval officers in 1853 and 1854, had been little concerned with trade.